ABSTRACT The title compound, [Mn3Fe6(C5H5)6(C6H4O2)6(C10H8N2)(H2O)2]n, consists of two crystallographically unique Mn(II) centers. One is situated on an inversion center and is octahedrally coordinated by two N atoms from two bridging 4,4'-bipyridine (4,4'-bipy) ligands and four O atoms, two from different bridging ferrocenecarboxylate (mu2-FcCOO-; Fc is ferrocene) units and two from aqua ligands. The two halves of each 4,4'-bipy ligand are related by a center of symmetry. The second Mn(II) center is in a strongly distorted tetragonal-pyramidal geometry, coordinated by five O atoms, three from three mu2-FcCOO- units and two from a fourth, chelating, eta2-FcCOO- unit. The FcCOO- units function as bridging ligands to adjacent Mn(II) centers, leading to the formation of linear ...Mn1Mn2Mn2Mn1... chains. Adjacent chains are further bridged by 4,4'-bipy ligands, resulting in a two-dimensional layered polymer.